s1_reader: refactor track_burst_num + optional noise + add safe_filename

[yunjunz]

• s1_reader: add get_track_burst_num() to read the start/stop burst number info from ESA. This returns a dict, which could simplify the logic of converting the local burst num to the global version.

• s1_reader.burst_from_xml(): skip reading the noise annotation files if not necessary, to support downloaded metadata using asfsmd without noise/slc data

• s1_burst_slc.Sentinel1BurstSlc: add new field "file_id"

• s1_burst_slc.Sentinel1BurstSlc: adjust the swath_name() from the previous version of burst IDs to the latest ESA's version (#47).

[yunjunz]

Thanks @yunjunz for these fixes. I have not tested the PR yet (I am planning to do that pretty soon). In the meantime, I have left a couple of comments. The most important is related to how the logging of the warning messages is performed. At the moment, we are using pyre inherited from ISCE3.

I see both print() and warnings.warn() are currently used in s1_burst_slc.py. In _burst_from_zip(), there is no message at all, if no TIFF file found (https://github.com/opera-adt/s1-reader/blob/71e2c9e589f9e010b4952a574fcda83806561339/src/s1reader/s1_reader.py#L644); while in _burst_from_zip() as modified in this PR, I changed it from warning.warn() to print().

My main motivation is that: a lot of these warnings while testing with metadata only (downloaded from asfsmd) are annoying and not helpful.